A gas supply system for producing high purity graphite products

Abstract

The application provides a gas supply system for preparing high-purity graphite products, which comprises a gas preheating pipeline, which is embedded in resistance material or heat preservation filler and used for preheating gas; a gas supply pipeline connected with the gas preheating pipeline, wherein the gas supply pipeline is provided with a plurality of gas outlets; a reaction chamber in communication with the gas outlets of the gas supply pipeline, wherein the reaction chamber is provided with flow guide filler for guiding gas circulation, the graphite products are located in the reaction chamber, and the pores between the graphite products and the reaction chamber are filled with the flow guide filler; and an exhaust pipeline in communication with the top of the reaction chamber. The gas preheating pipeline is embedded in the resistance material or the heat preservation filler, so that the purified gas is preheated, the temperature difference in the purification process is reduced, and the problem of uneven impurity content is alleviated.

Description

Technical Field

[0001] This application relates to the field of graphite product preparation, and more particularly to a gas supply system for preparing high-purity graphite products. Background Technology

[0002] Graphite products, such as molds, electrodes, and graphite felts, are made from raw materials such as coke, petroleum coke, and coal tar pitch through processes including batching, crushing, mixing, isostatic pressing, calcination, impregnation, and graphitization. Associated minerals in the raw materials and process contamination during production can introduce various impurities into graphite products. During the graphitization stage, the temperature of graphite products reaches 2300–3000 degrees Celsius. Under these high temperatures, most impurity elements in graphite products appear in the form of compounds, primarily high-melting-point, non-volatile oxides such as SiO2, Al2O3, FeO, CaO, P2O5, and CuO.

[0003] Graphite products are mostly used in high-temperature environments, where non-volatile impurities can be continuously released and contaminate related products, leading to a decrease in yield, especially for products with very high purity requirements, such as semiconductors and crystalline silicon. During the high-temperature sintering of semiconductor ceramic wafers, impurities from the graphite mold encapsulating the semiconductor can volatilize and contaminate the semiconductor ceramic wafers; similarly, during the preparation of crystalline silicon materials, impurities from the graphite electrodes used in the crystalline silicon furnace can volatilize and contaminate the crystalline silicon.

[0004] Currently, the main method for purifying graphite products is chlorine roasting. This involves reacting strong oxidizing halogen gases such as chlorine with oxides in graphite at high temperatures, generating volatile halide salts that evaporate from the graphite. For example, patent number 202411193365.0, entitled "A Method for Improving the Purity and Uniformity of Graphite Products for Semiconductors," describes a method where purifying gases such as chlorine halogen gases, carbon tetrafluoride, or fluorocarbons are introduced into the graphite product through a vent pipe at the bottom of an Atcheson furnace. These gases react with impurities to generate volatile substances that escape, thus achieving purification.

[0005] The initial temperature of the purified gas is low, and the temperature gradually increases after entering the Atchison furnace. The higher the temperature, the easier it is for the purified gas to react with impurities. This results in different degrees of reaction in different parts of the graphite product, leading to uneven impurity content, especially at the bottom of the graphite product, where impurities are not easily removed at low temperatures, resulting in a significant difference in impurity content compared to the top of the graphite product. Utility Model Content

[0006] This application addresses the problem of uneven impurity content caused by temperature differences in purified gas in an Atchison furnace by proposing a gas supply system for preparing high-purity graphite products.

[0007] A gas supply system for preparing high-purity graphite products includes: A gas preheating pipeline, which is embedded in resistive material or thermal insulation filler, is used for gas preheating; A gas supply pipe connected to a gas preheating pipe, wherein the gas supply pipe is provided with several gas outlets; A reaction chamber connected to the outlet of a gas supply pipeline is provided with a flow-guiding packing to guide the gas flow. A graphite product is located in the reaction chamber, and the pores between the graphite product and the reaction chamber are filled with the flow-guiding packing. An exhaust pipe that connects to the top of the reaction chamber.

[0008] To ensure sufficient preheating of the purified gas, preferably, the gas preheating pipeline includes a serpentine coil, which is embedded on both sides of the resistive material and adjacent to the insulation filler.

[0009] To better secure the serpentine coil, preferably, the gas supply system for preparing high-purity graphite products also includes a graphite mounting plate, which is located at the boundary between the resistive material and the insulating filler, and is detachably connected to the serpentine coil.

[0010] Furthermore, the graphite mounting plate is connected to the serpentine coil via clamps.

[0011] Furthermore, the gas supply system for preparing high-purity graphite products also includes a heat exchanger to recover heat from the waste gas. The tube side of the heat exchanger is connected to the exhaust pipe, and the shell side of the heat exchanger is connected to the gas preheating pipe.

[0012] Furthermore, the gas supply system for preparing high-purity graphite products also includes a condenser, the inlet of which is connected to a heat exchanger via a pipe to separate the solid substances condensed in the waste gas.

[0013] Furthermore, the gas supply system for preparing high-purity graphite products also includes a spray tower, which is connected to the outlet of the condenser via a pipeline.

[0014] The technical advantage of this application is that it embeds the gas preheating pipeline in the resistive material or heat-insulating filler, thereby preheating the purified gas, reducing the temperature difference during the purification process, and thus alleviating the problem of uneven impurity content.

[0015] The reaction chamber of this application is equipped with packing material to guide gas flow, which reduces the upward flow rate of gas and makes the gas flow more dispersed. The packing material also heats the gas, thereby reducing the temperature difference and allowing impurities to react more fully with the purified gas.

[0016] The relatively enclosed environment of this application can reduce the escape of purified gas and lower the cost of using purified gas.

[0017] The reaction chamber of this application is equipped with an exhaust pipe to guide the exhaust gas out, thus preventing the exhaust gas from causing harm to the staff. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the gas supply system for preparing high-purity graphite products according to this application; Figure 2 This is a schematic diagram of the gas supply system for preparing high-purity graphite products according to this application placed in an Atchison furnace; Figure 3 This is a schematic diagram of the gas supply system for preparing high-purity graphite products according to this application. Figure 4 This is a partial cross-sectional view of the gas supply system for preparing high-purity graphite products according to this application.

[0019] Explanation of reference numerals in the attached drawings: 1. Gas preheating pipe; 101. Serpentine coil; 102. Graphite mounting plate; 2. Gas supply pipe; 3. Reaction chamber; 301. Flow guiding packing; 4. Exhaust pipe; 5. Heat exchanger; 6. Condensate tank; 7. Spray tower; 8. Resistance material; 9. Thermal insulation packing; 10. Graphite products. Detailed Implementation

[0020] The following will be combined with the appendix Figures 1-4 The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0021] Example 1 Please refer to Figure 1 , Figure 2 and Figure 4 A gas supply system for preparing high-purity graphite product 10 includes: a gas preheating pipe 1, which is embedded in a resistive material 8 or a heat-insulating filler 9 for gas preheating; a gas supply pipe 2 connected to the gas preheating pipe 1, which has several gas outlets; a reaction chamber 3 connected to the gas outlets of the gas supply pipe 2, which is provided with a flow-guiding filler 301 to guide gas flow, the graphite product 10 is located in the reaction chamber 3, and the pores between the graphite product 10 and the reaction chamber 3 are filled by the flow-guiding filler 301; and an exhaust pipe 4 connected to the top of the reaction chamber 3.

[0022] The gas preheating pipe 1 is made of a corrosion-resistant and high-temperature-resistant material, such as graphite or silicon carbide. From a cost perspective, graphite is preferred for the gas preheating pipe 1. The gas preheating pipe 1 introduces the purified gas into the gas supply system of this application and preheats the purified gas. Since the gas supply pipe 2 is located below the graphite product 10, the gas supply pipe 2 can be embedded in the insulation packing 9. The purified gas then enters the reaction chamber 3 through the gas supply pipe 2 to react with impurities in the graphite product 10, generating products with lower melting and boiling points, which are then vaporized and discharged under high temperature. For example, if the purified gas is chlorine, then chlorine reacts with the non-volatile impurity alumina to generate aluminum chloride. Alumina has a boiling point of 2980 degrees Celsius, while aluminum chloride has a boiling point of only 180 degrees Celsius. Thus, after the impurities become more volatile products, they are more easily vaporized and discharged under high temperature, thereby reducing the impurity content of the graphite product 10.

[0023] The flow-guiding packing 301 in reaction chamber 3 is made of high-purity graphite particles with a particle size of 1-8 mm and an ash content of less than 0.01%.

[0024] After the purified gas removes impurities from the graphite product 10, it cannot be completely consumed. The remaining waste gas is highly corrosive and will corrode the relevant equipment of the Atcheson furnace, while also endangering human health and causing environmental pollution. Therefore, the purified gas cannot be exhausted using the original piping system of the Atcheson furnace. This application installs an exhaust pipe 4 at the top of the reaction chamber 3, and the waste gas will be specially treated in the subsequent exhaust pipe 4.

[0025] Example 2 Please refer to Figure 3 In this embodiment, based on Embodiment 1, one or more sections of the gas preheating pipe 1 are designed as serpentine coils 101. The stroke of the serpentine coil 101 is much greater than that of the linear pipe, while occupying less space. The serpentine coil 101 is embedded in the resistive material 8. The resistive material 8 heats the graphite product 10 while simultaneously heating the serpentine coil 101, thereby heating the purified gas within the serpentine coil 101.

[0026] In a preferred embodiment, this application includes two serpentine coils 101, embedded on both sides of the resistive material 8. The two serpentine coils 101 can be connected in series or in parallel. However, considering that the purified gas is heated for a longer time and the temperature rises higher when connected in series, the serpentine coils 101 are preferably connected in series.

[0027] Example 3 This embodiment adds a graphite mounting plate 102 to the second embodiment. The graphite mounting plate 102 is located at the boundary between the resistive material 8 and the thermal insulation filler 9, and is detachably connected to the serpentine coil 101. The graphite mounting plate 102 mainly facilitates the positioning and disassembly of the serpentine coil 101. The serpentine coil 101 needs to be connected to the gas supply pipe 2, and its position is relatively fixed. If it is not placed properly, the adjustment time required when connecting it to the gas supply pipe 2 will be long. By setting the graphite mounting plate 102, the serpentine coil 101 is fixed on the graphite mounting plate 102. Whether the graphite mounting plate 102 is tilted or offset is easy to judge, thus making positioning and disassembly more convenient.

[0028] Example 4 This embodiment further defines the fixing method of the graphite mounting plate 102 and the serpentine coil 101, namely, the connection by clamps. This facilitates the maintenance and replacement of either the graphite mounting plate 102 or the serpentine coil 101. In addition, a limiting groove can be provided on the graphite mounting plate 102 to secure the serpentine coil 101 to it. The graphite mounting plate 102 has sufficient supporting strength and will not introduce new impurities into the system.

[0029] Example 5 This embodiment adds a heat exchanger 5 to the gas supply system to recover heat from the waste gas. The temperature during the purification process reaches over 2000 degrees Celsius, resulting in very high exhaust gas temperatures and significant heat recovery value. This application utilizes heat exchanger 5 to recover heat from the waste gas. The recovered waste gas can be used for preheating the purified gas. In a preferred embodiment, heat exchanger 5 is a tubular heat exchanger 5. In the tubular heat exchanger 5, the waste gas flows through the tubes, and the purified gas flows through the shell.

[0030] Example 6 This embodiment further adds a condenser 6 to the gas supply system. Many vaporized impurities turn into solids after cooling. Direct emission of these would generate dust. Spraying would also increase the salt content of the water. By separating these solids from the waste gas through the condenser 6, the cost of subsequent gas treatment can be reduced. At the same time, some fixed components also have certain economic value and can be further separated and purified.

[0031] Example 7 This embodiment further adds a spray tower 7 to the gas supply system. The spray tower 7 is mainly used to remove acidic gases from the waste gas, such as hydrogen fluoride, chlorine, hydrogen chloride, etc. Through acid-base neutralization, neutral salt substances are generated. Simultaneously, the spray tower 7 also removes dust from the waste gas, thereby achieving the purpose of purifying the waste gas.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A gas supply system for preparing high-purity graphite products, characterized in that... include: Gas preheating pipe (1), which is embedded in resistive material (8) or thermal insulation filler (9) for gas preheating; A gas supply pipe (2) is connected to a gas preheating pipe, and the gas supply pipe (2) is provided with several gas outlets; A reaction chamber (3) is connected to the outlet of the gas supply pipe (2). The reaction chamber (3) is provided with a flow guide packing (301) to guide the flow of gas. A graphite product (10) is located in the reaction chamber (3). The pores between the graphite product (10) and the reaction chamber (3) are filled with the flow guide packing (301). An exhaust pipe connected to the top of the reaction chamber (3).

2. The gas supply system for preparing high-purity graphite products as described in claim 1, characterized in that: The gas preheating pipe (1) includes a serpentine coil (101), which is buried on both sides of the resistive material (8).

3. The gas supply system for preparing high-purity graphite products as described in claim 2, characterized in that: It also includes a graphite mounting plate (102), which is located at the boundary between the resistive material (8) and the thermal insulation filler (9), and is detachably connected to the serpentine coil (101).

4. The gas supply system for preparing high-purity graphite products as described in claim 3, characterized in that: The graphite mounting plate (102) and the serpentine coil (101) are connected by clamps.

5. The gas supply system for preparing high-purity graphite products as described in claim 1, characterized in that: It also includes a heat exchanger (5) to recover heat from the exhaust gas. The tube side of the heat exchanger (5) is connected to the exhaust pipe (4), and the shell side of the heat exchanger (5) is connected to the gas preheating pipe (1) 1.

6. The gas supply system for preparing high-purity graphite products as described in claim 5, characterized in that: It also includes a condenser (6), the inlet of which is connected to the heat exchanger (5) via a pipe to separate the solid substances condensed in the exhaust gas.

7. The gas supply system for preparing high-purity graphite products as described in claim 6, characterized in that: It also includes a spray tower (7), which is connected to the outlet of the condenser (6) via a pipe.

Images